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Finding the Fourth Proportional to 99.21, 136.79 and 81.66

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Solution

The fourth proportional to 99.21, 136.79 and 81.66 is: 112.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.21 : 136.79 = 81.66 : x
  2. Step 2: Convert to fraction form
    99.21/136.79 = 81.66/x
  3. Step 3: Cross multiply
    99.21x = 136.79 × 81.66
  4. Step 4: Simplify right side
    99.21x = 11,170.27
  5. Step 5: Solve for x
    x = 11,170.27/99.21
  6. Step 6: Final answer
    x = 112.59

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.